1. Technical Field
The present invention relates to improvements in network design and in particular to improved methods and systems for quality of service assessment for multimedia traffic within a network. Still more particularly, the present invention relates to a method and system for quality of service assessment for multimedia traffic under aggregate traffic conditions in a shared transmission medium.
2. Description of the Related Art
No where has the explosion of modern technology been more evident than in the field of communication. The number and type of communication services has been rapidly expanding, including so-called "multimedia" services such as video teleconferencing, video/movies on demand and the like.
The intermixing of these multimedia services with traditional data and voice communications within a shared transmission medium has presented various design problems. For example, a system which receives packetized telecommunication traffic from multiple multimedia services typically places the received packets within a queue within either a central queue or within a queue which is dedicated to a particular service. This can occur, for example, in ATM networks wherein multiple users subscribe to diverse services, such as video-conferencing and data retrieval, and share the same network.
Since a system can typically process, at most, n packets per time unit, if there are more than n subscribers for the services, the received packets are not immediately processed by the system but instead are queued either in one central queue or within a queue dedicated to a particular service, for future processing. During heavy use periods, these queues may become quite large and packets may be selectively discarded based upon a priority scheme.
Three network quality of service measures are of prime importance to network designers. Network designers must consider the maximum packet loss rate within the network, the maximum delay for a packet traversing the network and the maximum jitter (delay variation) which packets experience during network traversal. These three measures are utilized to indicate the quality of service within a network. In order to efficiently design a multimedia network, an accurate assessment of the quality of service measures is necessary, so as to satisfy customer expectations, build the network economically and utilize the network efficiency. Since diverse multimedia services may have diverse quality of service requirements, it is desirable to provide a technique for calculating quality of service values rapidly with as few traffic parameters as necessary so as not to waste network bandwidth on measurements.
In the past, attempts at statistically modeling aggregate traffic which originates from homogenous services with similar traffic types and similar characteristics have been proposed. For example, the Poisson Process is widely utilized to model aggregate traffic from voice sources. Similarly, the discreet Auto Regressive Process has been utilized to model aggregate traffic from video-teleconferencing sources. A Markov Modulated Poisson Process is often utilized to model aggregate traffic from data sources. These techniques typically required complex mathematical expressions which are not explicit and which required time-consuming numerical methods to solve. In high speed multimedia networks, the assessment of quality of service value must be performed rapidly and in real-time. Furthermore, prior art techniques for assessing quality of service within a network did not distinguish between networks which utilize a central queue and networks which utilize multiple queues, that is, one queue per service.
Thus, those skilled in the art will appreciate that a method and system for accurately and efficiently assess calculating the quality of service of multimedia traffic within a shared transmission medium would greatly enhance the efficiency of a network design and the level of customer satisfaction.